Booster pump throat



Paa'med Apr. 6, 1943 UNITED I STATES PATENT "OFFICE aoos'ran rum'rnaon'r William J. Lockett, Los Angeles', can, assignor to ThompsonProducts, Incorporated, Cieve- 1 land, Ohio, a corporationof OhioApplication January '14, 1942, Serial- No." 426,691

9 Claims. (Ci.103--11 1) This invention relatesto a booster pumpconstruction adapted for use in a fuel system to pressure liquid fuelwhile separating gases and vapors from the fuel as it is beingpressured.

More specifically, this invention relates to an inlet throatconstruction for a centrifugal type of booster pump which coacts withthe pumpimpeller to efliciently effect a separation of .gases and vaporsfrom liquid fuel flowing theretlirough without causing any dropin thesimultaneous pressuring of the liquid fuel in the fuel system.

While the'invention will be specifically de'-' pump thusnot onlyreceives a morestable liquidscribed in connection with aircraft fuelsystems,

itshould be understoodthat the invention is notlimited to-suchusebutis-broadly applicable to anysystem wherein it is desiredto deliver onlyfullyliquid materialfrom a source containing the liquid admixed withgases and vapors or having highly volatile ingredients therein. Theinvention is particularly. applicable for use in 'fuel systems for theprevention of vapor lock therein.

It hasbeen found possible to actually beat out air, other gases, andvapors from a pondof fuel by agitating the fuel below the hydraulicgradient of the pond. By using a centrifugal booster pumphavinga'ilarecl inlet throat, the fuel is subjected-t0. a whirlpoolaction by the impeller thereof as the fuel leaves the pond and flowsinto I the pump inlet, whereby the lighter gaseous bubbles are thrownupwardly and outwardly into the pond while fully liquid fuel isdelivered under pressure to the deliveryline of the fuel systeml Inother 'words, gases and vapors dispersed throughout liquid in a pondwhen the liquid is subjected to agitation are beaten out ofthe liquid byforming the same into;bubbles which-rise through the pond and burst intothe atmosphere at the top of the pond. This beating of the liquidnotonly'creates bubbles from-the occluded gases and vapors in the liquidbut also induces'the liberation of such gases and" vapors still held indissolved form in the liquid. The volatiles dissolved in the liquidwhich .are about to'separate'from' the liquid as'gas'e'sor vapors arecaused to separate in the form of newly created-bubbles produced by thebeating action. As a result, the

liquid is not only freed from occluded gases and vapors but isstabilized against the generation of additional occluded gases orvapors.

In the operation ofaircraft with gasoline or other volatile liquid as afuel, it is'well known that, as the atmospheric pressure drops with increase inaltitude, a point is finally reached where the'air and fixedgases .in solution start to evolve, and the lighter constituents in thefuels are varise to what is known in the art as fuel system having aninlet throat which effects a greater liberation of gases and vapors from.porized, until the engine fuel pump is no longer 1 capable ofdelivering fuel in a fully liquid form to'theengine carburetor.

duently'gives v vapor-lock. The agitation ofithe fuel by the Thiscondition freengine pump serves'to aggravate the difllculties that maybe experienced, by ,accelerating the e separation of air or air-fixedgases or vapors from the liquid fuel. In accordance with the presentinvention, howeven. thesegases and vapors are liberated from the fuelbefore they reach the engine fuel pump, and the gas and vaporfreed fuelis maintained'under pressure as it is fed to the engine fuel pump, sothat the vaporlock conditioncan'not occur. The engine fuel fuel, butreceives this fuel under pressure.

' The centrifugal type of booster usually 'emplayed for such gas andvapor separation includes an impeller'whosevanes are overlapped by aninlet throat with the amount of overlap and the speed of the impellerdetermining the ever,"when the inletthroat opening is enlarged, thevanes on the pump impellervmust be lengthened to maintain the pumpingcapacity and the "proper pressuring of the fuel delivered to'the fuelline by retaining. substantially the same overlapping of the vanes bythe throat.. This enlargement of the parts requires additional powerfor-maintaining the agitating speed of the im- 4 peller and consequentlyincreases the expense of operationvand the ultimatecost of manufacturingthe pump device.- 1

The present invention seeks to eflicientiy increase the gas and vaporseparation capacity of booster pumps while at the same time maintain ingthe desired pumping capacity for the pump without any enlargement of thepump parts and without increasing the pump speed. This is effected notonly by opening up the inlet to the pump but by'also shaping theinletthroat in a particular manner.

It is then an important object of the invention to increase the bubbleseparation and liberation efficiency of booster pumps by opening up theinlet throats of such pumps.

Another object of this invention is to provide a highly eflicient pumpconstruction for a fuel system wherein gases or vapors are more fullyliberated from a'liq'uid fuel flowing into the pump. 1 Another object ofthis invention is the provision of a centrifugal type of fuel pump for aliquid fuelfiowing to the pump without unduly sacrificing the pumpingcapacity of the pump.

A further object of this invention is the provision of an inlet threatfor a centrifugaltype of fuel pump which is so shaped as to coact withthe impeller of the pump to effect a highly effi- It has been found thatby enlarging theshown).

tic of the present invention are set forth with.

particularity in the appended claims. The in-' vention itself, however,both as to its organization and manner of construction, together withfurther objects and advantages thereof, may best be understood byreference to the following detally engage within and seat on thesurfaces 21 and 28 of the pump casing. Connection therebetween iseffected by flat-head screws 29. The screws 29 are inserted throughopenings 29a each having a tapered end portion 29b for seating theheaded ends of the screws. The threaded portions of the screws arethreaded into openings provided in the pump casing as shown in scriptiontaken in connection with the accompanying drawing, in which:

Figure 1 is a fragmentary vertical cross-sectional view, with parts inelevation, of a portion of a fuel system illustrating a booster pumphaving an inlet throat constructed in accordance with the principles ofthe present invention;

Figure 2 is a, plan view of the booster pump ,throat and the underlyingimpeller construction of this invention as seen when looking in thedirection of the arrows taken substantially in the plane indicated bythe line II-IIof Figure 1;

.Figure 3 is a bottom view of the inlet throat shown in Figure 2; and,

Figure 4 is an enlarged fragmental cross-sectional View showing thecurvature of the inlet throat opening and its overlapping relation withrespect to the pump impeller as seen. when taken substantially in theplane indicated by the line IV-IV of Figure 2.

In Figure 1, the reference numeral i designates the usual vented (notshown) gasoline tank for holding a pond P of gasoline or other volatileengine fuel. A booster pump assembly II is bolted to the bottom of thetank l0 around an aperture in said bottom by means of studs l2 threadedinto an annular abutment ring l3 seated in the tank on the bottom wallthereof. If desired, a gasket I 4 may be interposed between the boosterpump and the bottom of the fuel tank for tightly sealing the engagementtherebetween.

The pump assembly II is composed of a casing 5 shaped to define a pumpvolute chamber l6 and an outturned annular flange l'l receiving thestuds l2 therethrough,a throat ring 18, and an impeller l9 driven by a.shaft from a source of motive power such as an electric motor (not Theimpeller I9 is composed of a hub portion 2| keyed= or otherwise securedon the shaft 20 and maintained thereon by a nut 22. The impeller alsohas a disk portion 23 spanning the inlet opening 24 defined by thethroat ring l8. The disk 23 communicates around the periphery thereofwith the volute chamber I6 and has upstanding curved pumping vanes 25underlying the throat ring, as'best shown in Figures 1 and 2. Thepumping vanes 25 hav tapered inner end portions 26 disposed withinthe-inlet opening 24, which, as will be explained .hereinafter, serve asagitators or beaters for separating bubbles of gas and vapor from thefuel in .the pond P.

The pump casing l5 between the volute chamber I 6 and the outturnedflange I1 is so shaped as to-provide an annular shoulder 21 and asubstantially horizontal seat 28. The throat ring l8 has its outerperiphery shaped to complemen- Figure 1..

The outer periphery of the impeller, defined by the ends of the vanes25, is positioned between the throat ring l8 and an annular flangeportion 30 on the inside of the pump casing 15 in order that the fuel bedelivered under pressure through the volute chamber l6 into an outlet 3Lwhich is connected through a pipe line or tube 32 to the inlet of anengine fuel pump (not shown). A pump casing portion 33 houses the,driving shaft 20, which is connected to a source of motive power fordriving th impeller, such as an electric motor (not shown).

The throat ring l8 flares outwardly from the inlet opening 24 in axialdirections toward the top surface 34 and bottom surface 35 thereof, asbest shown in Figure 4. The'outward flare of the throat ring towards thetop surface 34 provides an enlarged mouth 36 in direct communicationwith the bottom of the pond P. The bottom portion of the inlet throat iscurved to provide a surface 31 lying directly above the fiat outerportion of the curved vanes 25 in such'a manner that th inlet throatoverlaps approximately one-third of the length of each vane. It is to benoted in Figure 4 that the curved surface 36 is described by a radius Aof much greater length than the small radius B which describes thecurved surface 31. These radii are struck from centers spaced from eachother but lying on a line C in closely spaced relation from the bottomsurface 35 of the throatring IS.

The center of the radius A, describing the surface 36, is so spaced fromthe top surface 34 of the throat ring that the surfaces are tangentiallyconnected. Likewise, the center of the radius B, describing the surface31, is so spaced from the bottom surface-'35 of the throat ring that thesurfaces are tangentially connected. Furthermore, the centers of radii Aand B are so spaced on the line C that the curved surfaces 36 and 31,formed as circle arcs, tagentially connect with each other.

It is to be understood, however, that although it is preferred to formthe inner periphery of the throat ring as described above, the broad.

aspects of this invention include arcs described .by various radii.

When the booster pump II is at rest, liquid fuel from the pond P canfreely flow through the pump inlet 24 along the open ended channelsdefined by the impeller disk 23 and the curved vanes 25 .into the volutechamber 16 where it can be withdrawn through the outlet 3! and pipe line32 into the fuel line for discharging the liquid fuel to the inlet sideof a fuel pump.

.Thus, even though the boosterpump II is at rest,.the usual fuel alwaysreceive fuel pump in a fuel system can on its suction side from the pondP.v

In the event that the fuel pump becomes inoperative, the booster pump IIcan pressure the fuel to the inletof the pump where it can be forcedtherethrough or by-passed therearound to feed fuel to an enginecarburetor connected to solid or fully liquid .material to the impeller.counter current circulation of fuel and bubbles is thus created in thetank, with the bubbles risimpeller 19 agitate the'fuel in the inlet 2!of the pump and actually beat out .bubbles G of gas and vapor from theliquid fuel. The bubbles G are exposed.

are thrown by the vanes outwardly along the flared-mouth 36 of thethroat ring and, being lighter than the liquid fuel, rise'through thepond P to the top thereof where .they burst at the surface and liberatethe entrapped gases and vapors to the atmosphere through the vent projvided in the tank [0. As shown in Figure 1, the bubble path widens outand the bubbles become larger as they approach the surface of the pondP.

The impeller vanes create a funnel-shaped whirlpool in the pond P, theparticles of which rotate in the same direction as the impeller and movein a corkscrew fashion toward it. This whirlpool extends well upwardinto the tank and is present assoon as the booster pump commences tooperate. As a result, the fuel freed from air and gases circulates, asindicated by the arrows, down through the whirlpool as a substantially Aing throughthe fuel outwardly from. the whirlpool and with the fullyliquid fuel being fed down, through the funnel-shaped whirlpool to theimpeller. Y i

The fully liquid fuel is then subjected to centrifugal action betweenthe vanes on the impeller and the throat member, where the lastremaining bubbles are forced from the fuel outcurved surface 3I,longerlengths of the blades the suction behind the revolving blades to moreeffectively generatebubbles of gases or vapors for liberation from theliquid fuel. Furthermore, any bubbles so generated tend to follow thecurved surface 31 by rising to a position in which the curved surfacesof the throat ring are tangentially connected where they are then thrownoutwardlyby the agitation of the vanes to follow along thecurved'surface 36 whence they con-' tinue to riseoutwardly andupwardly'away from the downwardly flowing fuel feed to the pump.

Consequently, the inner. peripheral shape of the throat ring [8 ofthepresent invention as sures a more eificient operation of thecentrifugal impeller for liberating gases and vapors from a liquid fuel.Fully liquid fuel is thereby pressured into the volute chamber l6 and ismaintained under pressure through the outlet 3| and the pipe line 32 tobe supplied to a fuel line.

The agitating vaneportions 26 not only beat, the occluded gases andvapors in the fuel into bubble form but also generate additional bubblesfrom dissolved gases or vapors about to beliberated from the liquid.Furthermore, the outer from of volatiles about to become vapors orgases,

wardly along the bubble path shown in Figure 1.

It has been found in actual operation that by a providing a curvedsurface 36 at theinlet side of the' throat ring l8, the bubbles G tendto follow the curvature of the surface either entirely or for a portionof its length and then break away to rise upwardly in a curved path, asillustrated.

' By forming the surface 36 curved instead of flat, 7

the bubbles G tend to follow the curvature of the surface after theybreak away from actual contact therewith thereby effecting a'funnel-shaped path of greater width at the bottom of the tank ill thanwould. be effected if the surface were I made flat and extendeddiagonally upward and outward. It has also been found that some of thebubbles G tend to be trapped, between the overlapping portions of thebottom surface of the throat ring it and the flat edge of the ,As theimpeller I9 is revolved at high speed, "a high suction is built up backof each of the revolving blades which causes the generation ofadditional bubbles of -gases or vapors to be liberated from the liquidfuel flowing through the pump .into the volute chamber thereof. highsuction back of the revolving blades causes a cavitation oranopenyspacezwhich is free of liquid fuel.. By increasing the throat openingimmediately above the impeller blades by the This whereby fully liquidfuel only flows into the volute chamber l6.

- When an aircraft isflown to an altitude wherethe fuel in the pond Pstarts breaking up because of the reduced pressure, scattered bubblesmay appear throughout the tank,' but as explained above, such bubblesare separated from the liquid fuel, -sothat only fully liquid sured intothe fuel line 32.

' In flying aircraft to high altitudes, the booster 'piunp H can bestarted before the fuel starts breaking, up in the pond, so .thatthefuel will become stabilized even at the sub-atmospheric pressuresencountered. As a result, the aircraft can be flown to much higheraltitudes, and

even though the fuel breaks up at these high altitudes, the booster'pump.will insure delivery of only fully'liquid fuelfrom the pond to the fuelline.

By immediately pressuring thebubble-free fuel in the volute chamber andby holding .this pressure above the vapor pressure of thefuel-throughout the entire path of flow of the liquid to the enginecarburetor, .additional gases "or vapors cannot be liberated.

While, as illustrated in Figure 1; it is preferred to mount the boosterpump II on the bottom of the tank ill, in some installations it may benecessary to mount the pump H on the side wall of the tank. It is onlynecessary that the impeller be so mounted as to lie below .the hydraulicgradient of the pond P. When so positioned,,the

fuel pressured by' the impeller into the volute chamber l6 will be freefrom entrainedgases or vapors.

From the'foregoing description, it will be apparent that the boosterpump described has two functions: the first, to separate out bubbles ofgas or vapor which form at the inlet, due to the This additional openingof the throat results in a greater cavitation and causes In other words,the

material. is presnecting an end surface of said ring.

' to said end surfaces.

agitation of the liquid, and elsewhere in the tank; and the second, topressure the fully liquid fuel to a fuel line. The improved inlet throatconstruction of this invention for such a booster pump increases the gasand vapor separation efliciency of the pump while maintaining fuelpressuring efficiency for the pump. Furthe more, this greater efiiciencyis effected without the need for providing additional power formaintaining the agitating speed "of the impeller.

While a particular embodiment only of this invention has beenillustrated, it will, of course, be understood that the invention shouldnot be limited thereto, since many modifications may be made, and,therefore, it is contemplated by the appended claims to cover all suchmodifications as fall within the true spirit and scope of the presentinvention.

I claim as my invention: I

1. In a pump having a driven impeller with vanes radiatingoutwardlytoward the periphery thereof, the improvement of aninlet throat for saidpump comprising a ring member having its whole inner periphery formed bycurved surfaces extending outwardly in opposite axial directions towardthe end surfaces thereof, one of said curved surfaces being described bya greater radius than the other of said curved surfaces, said ringmember overlapping the periphery of said impeller in closely spacedrelation therefrom with said other and shorter curved surface lyingadjacent said vanes.

2. In a pump having a driven impeller with vanes radiating outwardlytoward the periphery thereof, the improvement of an inlet throat forsaid pump comprising a ring member overlapping the periphery of saidimpeller in closely spaced relation therefrom, and means for removablysecuring saidring member to said pump, said 'ring member having itswhole inner surface formed by tangentially connected circle arcs ofdifferent radii, one of said arcs tangentially con 3. An inlet throatfor a pump comprising a ring member having a bore thcrethrough, saidbore being formed of tangentially connected circle arcs of differentradii extending in opposite axial directions toward the end surfaces ofthe ring member and being tangentially connected 4. An inlet throat fora pump comprising a ring member having a bore therethrough; said borebeing formed of tangentially connected circle arcs of different radiihaving their centers lying in a single transverse plane, said circlearcs extending outwardly in opposite axial directions toward the endsurfaces of the ring member and being tangentially connected thereto.

5. An inlet throat for a pump comprising an annular member having anaxial bore there through and a radially extending flange on the outerperiphery thereof, said flange having oir-' cumferentially spacedaxially extending'screw receiving openings therethrough for removaablyconnecting the member of the pump, said throatmember having spaced endfaces, and said axial bore being defined by tangentially connectedcircle arcs of :different radii extending in opposite axial directionstoward said end faces and tangentially terminating in connectiontherewith.

6. In a centrifugal pump having a driven im-' peller with a radial diskand upstanding curved anes thereon radiating outwardly toward theperiphery thereof, each of said vanes having an which comprises a ringmember overlapping said impeller in closely spaced relation therefromand having an internal bore lying between the outer ends of said vanesand their sloping edges, said internal bore being defined by circle a csof different radii extending outwardly in opposite axial directionstoward the end surfaces of said ring member, the circle arc of smallestradius extending toward said overlapped vane portions.

7. In a centrifugal pump having a driven impeller with a radial disk andupstanding vanes thereon radiating outwardly toward the peripherythereof, each of said vanes having its upper edgesloping inwardly fromsubstantially its midportion toward the axis of the impeller disk andhaving its upper edge at the outer portion thereof substantiallyparallel with said disk, the improvement of an inlet throat for saidpump comprising a ring member having an internal bore and an end surfacein closely spaced parallel relation with the upper edges at the outerportions of said vanes, said internal bore lying between said inner andouter portions of the upper edges of said vanes whereby the throat ringoverlaps said vanes for substantially one third of their lengths, saidbore being defined by connected curved surfaces of different radiiextending outwardly and in opposite axial directions, the curved surfaceof smallest'radius extending toward said overlapped vanes.v

8. In a centrifugal pump having a driven impeller for agitating agasifying source of liquid at its inlet to beat bubbles of gas from theliquid and deliver fully liquidfuel to its outlet, said impellerincluding a radial disk and curved vanes thereon radiating outwardlytoward the periphery thereof, the improvement of a removable inletthroat' for said pump comprising a ring member having an internal boreof less diameter than said impeller for partially overlapping the vanesthereon,v said internal bore being defined by connected curved surfacesextending outwardly in opposite axial directions toward the end surfacesof the ring member, said curved surfaces being described by differentradii with the curve of greatest radius opening into said gasifyingsource of liquid and thecurve of smallest radius extending toward saidoverlapped vanes whereby rota-' vanes thereon defining pumping channelscommunicating with the volute chamber, the improvementof an inlet throatfor said pump overlapping the outer portions of said vanes in closelyspaced relation therewith to define a Wall for said pump channels, saidthroat defining an inlet opening to the pumping channels and saidopening initially converging along a curved path and then divergingradiall along a curved path to the inner ends of the pumping channels tofacilitate release of bubbles from the channels,

WILLIAM J. LOCKET'II.

